Your bidding strategy determines how Google sets your cost per click, either manually (you set a maximum bid per keyword) or automatically (Google's algorithms adjust bids based on conversion probability). The right strategy depends on how much conversion data your campaign has accumulated. Using automated bidding without sufficient data is one of the most common causes of poor campaign performance for new Google Ads accounts.

The bidding strategy ladder

Think of bidding strategies as a ladder. You start at the bottom and move up as your campaign accumulates conversion data:

  • Rung 1 — Manual CPC: you set a maximum bid per keyword. Full control, requires active management.
  • Rung 2 — Enhanced CPC (ECPC): manual bids with automated adjustments. Google can increase your bid by up to 30% when it predicts a conversion is more likely. Requires some conversion history.
  • Rung 3 — Target CPA (tCPA): Google automatically sets bids to achieve your target cost per acquisition. Requires at least 30 conversions in a 30-day period to function effectively.
  • Rung 4 — Target ROAS (tROAS): Google optimises bids to achieve a target return on ad spend. Requires conversion value tracking and significant conversion volume.
  • Rung 5 — Maximise Conversions: Google spends your entire daily budget in a way it predicts will produce the most conversions. Can be effective once significant conversion data exists.

For most accounting firms, the relevant range is rungs 1 to 3. ROAS bidding requires conversion value data that most service businesses do not track.

Manual CPC — the starting strategy

Manual CPC is the right choice when your campaign has fewer than 30 conversions in the past 30 days, you want to learn how the platform works, or you are managing a new campaign with no conversion history.

With manual CPC, you set a maximum cost per click for each keyword or ad group. Google charges up to that amount when someone clicks your ad. You can set different bids per keyword; bid higher on your best-converting keywords and lower on exploratory terms.

Starting bid guidance for UK accounting keywords: local accounting keywords typically cost £2 to £8 per click. Start bids in the middle of the estimated first-page range shown in Keyword Planner. Adjust up on keywords generating conversions; adjust down or pause keywords spending without converting. Manual CPC requires regular attention, reviewing bids weekly and adjusting based on performance data.

Enhanced CPC — the transition strategy

ECPC keeps your manual bids as the baseline but allows Google to increase bids by up to 30% when its signals suggest a conversion is likely (time of day, device, location, search context). It is a bridge between full manual control and full automation. ECPC is worth enabling once your campaign has 15 to 20 conversions and some performance patterns are established. The automated adjustments are modest and the strategy still gives you control over base bids.

Target CPA — automated bidding for established campaigns

Once you have 30 or more conversions in a 30-day period, Target CPA automated bidding becomes viable. You set a target cost per acquisition (for an accounting firm, this might be £40 to £80 per enquiry) and Google adjusts bids automatically to achieve that target.

Target CPA works by analysing signals — time of day, device, location, audience, search query — and adjusting bids in real time to prioritise clicks from users most likely to convert. Over time, it typically outperforms manual bidding in terms of cost per conversion, once it has enough data to optimise. The risk of using Target CPA before you have sufficient conversion data is that Google has no meaningful pattern to learn from and will spend budget inefficiently.

Setting realistic CPA targets

For an accounting firm, what is a reasonable cost per enquiry? If your Google Ads budget is £500/month and you want 10 enquiries per month, your target CPA is £50. If you close three of those to clients at £1,000/year each, the £500 spend produces £3,000 in annual fees, a strong return. Set your initial Target CPA at your estimated cost per conversion from manual CPC data. If your manual CPC campaigns have been producing enquiries at £45 each, set your Target CPA at £50 to give Google some flexibility. Tightening it too aggressively reduces delivery volume.

What to avoid

Using automated bidding on a new campaign with no conversion history: the algorithm has nothing to learn from and will spend budget in patterns that may not align with your goals.

Switching bidding strategies too frequently: every time you change strategy, the campaign enters a learning phase. Give each strategy at least two to four weeks before evaluating.

Maximise Clicks bidding: this strategy maximises clicks regardless of quality. For accounting firms where the goal is enquiries (not traffic), Maximise Clicks often produces poor-quality traffic that does not convert.

Ignoring impression share metrics: if your manual CPC bids are too low, you may win a small fraction of available auctions. Check impression share (the percentage of eligible auctions where your ad showed) in your campaign reports; low impression share on your best keywords may indicate bids are too low.

Key takeaways

  • Start all new Google Ads campaigns on Manual CPC; switch to automated bidding only after accumulating 30 or more conversions.
  • Enhanced CPC is a reasonable bridge strategy with 15 to 20 conversions; it keeps manual bid control while allowing modest automated adjustments.
  • Target CPA automated bidding is the most appropriate strategy for established accounting firm campaigns with sufficient conversion history.
  • Set your initial Target CPA based on your actual cost per conversion from manual CPC data; do not set it aggressively below what manual bidding was already achieving.
  • Avoid Maximise Clicks; it optimises for traffic volume, not enquiry quality.

Frequently asked questions

How long does the automated bidding learning phase take?

Google's automated bidding enters a learning phase when first activated or after significant changes. Learning typically takes one to two weeks. During learning, performance may fluctuate; avoid making other major campaign changes during this period.

Should we use the same bidding strategy across all campaigns?

Not necessarily. A well-established core services campaign with 50 or more monthly conversions can use Target CPA, while a new niche campaign with limited conversions should start on Manual CPC. Match the strategy to the data available in each campaign.

What if Target CPA produces fewer conversions than manual bidding?

Check your Target CPA setting; it may be too aggressive (lower than what manual bidding was achieving). Also check whether the campaign has enough conversion volume to support automated bidding (30 or more per month is the minimum, 50 or more is more reliable). If conversions drop significantly after switching, revert to manual bidding and investigate.

Does bidding strategy affect Quality Score?

No. Quality Score is determined by ad relevance, expected CTR, and landing page experience, not by your bidding strategy.

What is Maximise Conversions bidding?

Maximise Conversions tells Google to spend your entire daily budget in a way that produces the most conversions, without a specific cost target. It can work well for high-conversion-volume campaigns but is prone to overspending on lower-quality conversions to hit volume targets. Target CPA (which sets a cost constraint) is generally more useful for accounting firms.

For more on bidding and Google Ads management, visit our Google Ads for accounting firms hub.